The present invention relates to a method for open-end spinning of yarns in a rotating spinning chamber. The fiber material in the form of a sliver is placed onto a continuously widening slip wall of the spinning chamber in the direction of sliver introduction. The angle of the slip wall relative to the axis of rotation of the spinning chamber is between 8.degree. to 12.degree., and the yarn is removed from the spinning chamber in a direction counter to the direction of introduction of the sliver through a yarn removal channel which is positioned along the axis of rotation of the spinning chamber.
Conventional spinning rotors for an open end spinning device comprise concentrical inner surfaces with a groove provided as a fiber material collecting location at the position of the greatest inner diameter of the rotor. The groove is formed by two surfaces, one of which is the so-called slip wall to which the fiber material in the form of a sliver is guided and the other is the so-called draw-off wall. In such spinning rotors the introduced fiber material is placed onto a collecting surface and glides into the slip wall in the form of a V-shaped groove where the fibers are compressed to form a band of a substantially triangular cross-section. The fiber material is then removed from this V-shaped groove along the draw-off wall. The resulting yarn is provided with a substantially circular mantle surface during this process, i.e., the resulting yarn has a substantially circular cross-section.
Such methods and the corresponding devices are substantially disclosed in German Offenlegungsschrift 17 10 038, 25 44 503, and 30 18 474 as well as in Swiss Patent 593 356.
According to a publication in "Melliand Textilberichte", 5/1995, pages 308, 310/311, the open end spinning method requires with respect to yarn quality that all fibers, when approaching the rotor groove, should have only a minimal differential velocity relative to the rotor. The time for reaching the rotor groove increases with
a longer gliding path, for example, when the fiber material impinges closer to the edge of the rotor; PA0 minimal starting velocity, for example, when the supplied vacuum is low; PA0 small fiber gliding angle .alpha., for example, required due to constructive considerations in small rotors, whereby the conventional values are .alpha. equal 12.degree. to 25.degree.; PA0 increased frictional coefficient, for example, when the rotor wall has a rough surface. PA0 providing a spinning chamber with an annular slip wall; PA0 placing a sliver of fiber material onto the annular slip wall widening continuously in a direction of sliver introduction into the spinning chamber, wherein an angle of the annular slip wall to the rotational axis of the spinning chamber is between 8.degree. and 12.degree.; PA0 forming a yarn from the fiber material in a yarn formation zone located within a portion of the annular slip wall upstream of a widest diameter of the annular slip wall viewed in the direction of sliver introduction; PA0 removing the fiber material as a yarn from the spinning chamber through a yarn removal channel, extending along the rotational axis of the spinning chamber, in a direction opposite to the direction of sliver introduction. PA0 a spinning chamber with an annular slip wall, wherein a sliver of fiber material is placed onto the annular slip wall widening continuously in the direction of sliver introduction into the spinning chamber, wherein the angle of the annular slip wall to the rotational axis of the spinning chamber is between 8.degree. and 12.degree.; PA0 the annular slip wall comprising preferably a yarn formation zone located within a portion of the annular slip wall upstream of a widest diameter of the annular slip wall viewed in the direction of sliver introduction; PA0 the spinning chamber having a yarn removal channel, extending along a rotational axis of the spinning chamber, for removing the yarn formed in the yarn formation zone, from the spinning chamber in a direction opposite to the direction of sliver introduction.
The prior art thus teaches that, when considering the aforementioned parameters, it must be ensured at all times that the fibers be deposited in the rotor groove.
Conventionally, textile spun yarns of staple fibers, independent of the type of spinning method, are designed to have a uniform circular cross-section. It is presumed that the thus structured yarns are used for producing fabrics by weaving, knitting, etc. which correspond to the conventionally desired products. Such textile fabrics have a uniform, knobbly surface structure, especially when yarns with a high degree of twist or twisted yarns are used.
When it is desired to provide the fabric with a special textile surface structure or when it is desired to produce special visual effects, specialty yarns must be used, for example, yarns with non-uniform or changing cross-section, for example, fancy yarns. It is also possible to provide such special effects by weaving, knitting etc. by providing a respective bonding or pattern for forming the surface of the textile cloth (fabric) or other textile materials.
It is therefore an object of the present invention to produce an open end spun yarn with a non-circular cross-section with which it is possible to change the textile surface appearance or surface structure only by using this special yarn or a twisted yarn made thereof.